Jpeters09

I purchased my 03 SS in January of 15' and it has always shifted a little slow, it hasn't gotten much worse since I flushed it and added lucas tranny stop slip to it. But the 2nd to 3rd shift is still not very healthy. I'm wondering if anyone has rebuilt these transmissions? I thought about maybe putting a very mild shift kit in as well when I have it all apart. I need suggestions on what rebuild kit to purchase, and any advice to which shift kit to install, or if thats a bad idea. I do body work for a living, but I have a very skilled mechanic friend who will be helping who has rebuilt a few transmissions before.